Thor Heyerdahl

Thor Heyerdahl, the Norwegian anthropologist who has died in Italy aged 87,
was propelled to fame by his remarkable crossing of the Pacific Ocean aboard
a balsa-log raft, the Kon-Tiki, in 1947.

12:10AM BST 19 Apr 2002

Against all prevailing expert opinion, Heyerdahl's researches had convinced him that ethnological traits common to Polynesia and South America were the result of pre-historic transoceanic migration by Peruvian Indians, perhaps around 500 BC.

Thor Heyerdahl holds a shark fished from the ocean in 1947 aboard the Kon Tiki

Academic orthodoxy held that Polynesia had been colonised from Asia, not South America, and that the journey of almost 5,000 miles central to Heyerdahl's heretical theories was beyond the navigational skills of a primitive people such as the Peruvians. The features common to the two cultures were said to be coincidental.

Since no publisher would print his thesis, Heyerdahl decided that only a recreation of such a voyage could give his ideas the necessary credibility. With five friends as crew, Heyerdahl constructed a 60 ft-long raft with sails, its design based on ancient pictures of Indian oceangoing vessels. The craft was named Kon-Tiki, after the mythical Polynesian hero Tiki, who was said in oral tradition to have led the ancestors of the islanders there from the East.

Heyerdahl had first heard the legend in the mid-1930s, while he was living in the Pacific on the Marquesas Islands, and had connected this Polynesian Aeneas with the Inca tale of Con-Tici, the fair-skinned king said to have fled from Peru across the ocean following the massacre of his race at Lake Titicaca some 500 years before the birth of Christ.

On April 28 1947, the Kon-Tiki pushed off from the Peruvian port of Callao. For 101 days it drifted across the Pacific, pushed towards Polynesia - as Heyerdahl had predicted - by warm currents and the south-east trade wind. The crew supplemented their US Army issue rations with freshly caught shark. Almost 4,500 nautical miles later, the raft grounded itself on the Raroia reef, and Heyerdahl waded ashore on Tuamotu Island, the southernmost tip of Polynesia.

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Although Heyerdahl had undertaken the voyage purely for scientific reasons, the exploit caught the world's imagination, and he found himself a much feted figure. In later years, he came rather to resent the celebrity the Kon-Tiki had brought him, arguing that it had pigeon-holed him as a daredevil explorer rather than as a man of science, and that this had made it harder for him to persuade his fellow academics of the veracity of his theories.

Certainly it was many decades before Heyerdahl, who was a man of few doubts, saw any of his anthropological ideas widely accepted, something that he put down to the jealousy of his rivals. But his fame undoubtedly brought him a wider audience for his theories, for his story of the intrepid voyage eventually sold more than 30 million copies and was translated into 67 languages.

Even this achievement, though, was not all plain sailing; when his manuscript was first offered to American publishers, it was rejected on the grounds that the public would not be interested in it as no one had drowned.

Thor Heyerdahl was born at Larvik, Norway, on October 6 1914, the only child of elderly parents. His father ran a mineral water plant and a brewery while his mother, a keen Darwinist, ran the town museum. He was schooled locally, and from an early age roamed the woods that ran down to the edge of the town and later made expeditions into the mountains by sledge with his pet husky. Despite his taste for adventure, he remained terrified of water after twice almost drowning as a boy, and did not learn to swim until he was 22.

At the University of Oslo, Heyerdahl read Zoology and Geography, but he had already become fascinated by Polynesia. He soon decided to write his doctorate about the Pacific islands.

He had, however, by now also become convinced that what was accounted progress by civilisation was no such thing when it took mankind further away from nature, and determined to try to live as ancient man had done. Thus on Christmas Eve 1936, he and his new bride, Liv, set off for a year-long honeymoon on Fatu-Hiva, in the Marquesas chain.

The experiment proved not wholly successful. On arrival on Fatu-Hiva, Heyerdahl discovered that the natives were suffering from a range of ailments induced by contact with Europeans which included leprosy and elephantiasis.

He therefore resolved to live in isolation from them, and for some months he and Liv existed on roots and berries and river prawns, although they soon discovered that the modern stomach struggled with the diet of man's forebears. Liv was struck down by disease, and Heyerdahl had to call on modern medicine to save her.

His time on the island had, however, not been entirely without benefit. After accidentally falling into a river, Heyerdahl discovered that he could swim: "I realised that the ocean buoyed me up instead of sucking me down," he wrote later. It was also on Fatu-Hiva that he heard, from a former cannibal, the story of Tiki. Heyerdahl recounted his experiences on the island in Green was the Earth on the Seventh Day (1998).

While excavating sites in British Columbia in search of evidence to support his theories of transoceanic cultural pollination, Heyerdahl was stranded, almost penniless, in Vancouver by the outbreak of the Second World War. After a variety of labouring jobs, he eventually made his way to England and joined the Free Norwegian Army, where he was trained as a saboteur and wireless operator, although several aborted missions meant that he never saw action.

After the success of the Kon-Tiki expedition, which in 1951 brought him the Oscar for Best Documentary Film, Heyerdahl set up a museum to house the vessel in Oslo and then concentrated on the archaeological search for further proof of his theories. He led digs in Bolivia, Ecuador and Colombia, and in Peru itself discovered raft centreboards which suggested that return voyages from Polynesia against the wind might have been possible.

He also excavated extensively on Easter Island, the statues of which were for him proof of white-race migration. This idea was, however, later contradicted by genetic testing and to his credit Heyerdahl, as a scientist, accepted the primacy of this new evidence.

But his conviction in the existence of links between ancient peoples was not diminished, and in the late 1960s he began to make plans for another sea voyage after seeing Inca pottery which depicted reed ships resembling those of Pharaonic Egypt. Other parallels between the two civilisations included stepped pyramids, mummification, calendars and hieroglyphs, and Heyerdahl began to wonder if Mediterranean culture had arrived in America before Columbus.

Chad was the only African country where traditional boatmaking skills had survived, and accordingly local shipwrights were hired to construct a 50 ft sloop from Ethiop papyrus. Heyerdahl chose his crew to reflect racial harmony, including a Russian, an American and one of the boatbuilders.

The vessel, named Ra, left the Moroccan port of Safi on May 25 1969. Having covered 2,800 miles in two months, it was struck by a storm 600 miles off Barbados and, because of a fault in the design, became waterlogged. Despite the protests of his crew, Heyerdahl abandoned the boat, but in July 1970 successfully crossed the Atlantic in another reed boat, Ra II.

But while the notion of cross-Pacific migration is no longer anathema to ethnologists, that of cross-Atlantic cultural pollination remains much more contentious, in part because the great civilisations of South America flourished long after that of Egypt, making direct influence unlikely.

While making this voyage, Heyerdahl had observed early signs of oil pollution in the ocean, and he now became an outspoken campaigner on environmental issues; he was eventually appointed special adviser to the UN on the subject.

His voyages had also convinced him of the essential unity of mankind ("The ocean does not separate us - it unites us," he said), as well as of the need for Europe to be modest about its role in civilising the globe; Heyerdahl was fond of pointing out that the continent was the last, apart from Australia, to have become civilised, and that architecture, astronomy and even religion all began elsewhere.

These beliefs underpinned the last of his epic voyages, which took place in 1977. Heyerdahl hoped to show that the ancient cultures of Arabia could have disseminated their ideas to Africa and Asia, and to this end recreated a Sumerian reed ship, which he then triumphantly sailed down the Tigris, across the Persian Gulf and then back towards the Red Sea.

But its progress was halted by North Yemen's refusal to let it enter its waters, and with war raging all around him, Heyerdahl burnt the boat at Djibouti as a protest against the folly of man.

He remained active into later life, and after many years living in Italy based himself on Tenerife, whose stepped pyramids suggested to him a connection with the culture of Peru. Despite his earlier prejudices about progress, he became an avid user of the internet and e-mail, rising at six every morning to deal with his correspondence from around the world.

Inevitably, his beliefs in world federalism, and his investigations into a cataclysmic event about 5,000 years ago - perhaps a great flood - which he believed to have acted as a catalyst for civilisation across the globe, meant that he acted as a focus for cranks with theories about Atlantis, but he dismissed such ideas as "fairytales". He remained, however, an admirer of primitive societies. He was also an atheist.

Heyerdahl stayed trim and dapper into old age, his appearance aided by his daily practice (even as an octogenarian) of digging a large hole in his garden with a pick and a shovel. When young he had slightly resembled a dimple-free Kirk Douglas; as an old man, his mane of white hair and single-minded manner gave him something of the aspect of the Ancient Mariner. Earlier this month, he stopped taking food and water, after being diagnosed with a terminal brain tumour.

Thor Heyerdahl was awarded the Royal Gold Medal of the Royal Geographic Society in 1964. He published an elliptical autobiography, In the Footsteps of Adam, in 2000. The previous year he had been voted Norwegian of the Century.

He married first, in 1936 (dissolved 1947), Liv Coucheron Torp. He married secondly, in 1949 (dissolved 1979), Yvonne Dedekam- Simonsen. He married thirdly, in 1996, Jacqueline Beer, a former Miss France. He is survived by her, and by two sons of the first marriage and by two daughters of the second; another daughter of that marriage predeceased him.